A method of this kind relates in particular to the control of an adjuster which has at least one adjusting path between a first stop and a second stop and in which an adjustment position of the adjuster can be set within the adjusting path by a user action. The relevant adjustment position within the adjusting path is hereby determined (by means known per se for position detection) and an (electrically acting) protective stop is set in the adjusting path so as to trigger an automatic reduction in the adjusting energy in dependence on the adjustment position, more particularly to stop the adjusting movement in the vicinity of a mechanical block for the adjusting movement. The mechanical blocking can thereby be triggered by one of the two mechanical stops at the limits of the adjusting path or by an obstruction in the adjusting path, such as for example a drinks carton located behind the vehicle seat.
A user action may include an operation of an actuating device associated with the adjustment device by the person located on the corresponding vehicle seat with which the adjustment position of the vehicle seat or of a part of the vehicle seat which is to be adjusted can be changed. An electrically acting protective stop may include a protective stop which is not formed through a mechanical stop but which rather acts electrically on the adjusting movement of the adjuster in order to brake same.
Control processes for adjusting devices of motor vehicles used up until now use a direct measuring system for determining the adjustment position of a vehicle seat. For this a potentiometer detects the relevant actual adjusting position along an adjusting path. Each adjustment position is assigned a resistance value. Through the direct coupling between the resistance value and the adjusted movement no errors generally arise between the measured position and the actual adjustment position when the measured value can be read fault free from the potentiometer.
As a result of the high wear on the potentiometers for path measuring and the cabling additionally required there is now an increasing use of path detection systems for controlling vehicle seat adjusters which detect the rotational drive movement of the drive motor for determining the position. For this purpose for example the motor current is evaluated or the drive movement is detected by means of sensors. In particular Hall sensors can be used for a detection of this type. This type of indirect measuring of the adjustment position by detecting the drive movement however leads to measuring errors as a result of inaccuracies between the detected position and the actual adjustment position which can differ here significantly from each other. These inaccuracies can only be eliminated in part by program technology. If an adjuster on a vehicle seat is actuated repeatedly, for example through frequent change of driver then this can lead to significant position errors.
The position detection systems previously described for vehicle adjusters are used for the controlled starting up of previously stored memory positions which can be configured in an adjustment path between a first mechanical stop and a second mechanical stop. For configuration it is used that the adjustment position within the adjusting path is determined via one of the previously mentioned position detection systems.
In addition to this comfort function a protective stop is set in the adjusting path in the vicinity of a mechanical stop in order to reduce the mechanical strain on the adjusting system. The protective stop thereby enables in dependence on the determined adjustment position an automatic reduction in the adjusting energy. This reduction enables a smooth braking of the adjusting movement. In the ideal case the part of the adjuster which is to be adjusted does not quite reach the mechanical stop. In order to ensure this even whilst including further factors or tolerances the drive motor is electronically braked or switched off for example in the region of the protective stop which leads to stopping of the adjusting movement of the adjuster in the vicinity of this protective stop.
The significant position errors previously explained moreover cause a displacement of the positions of the protective stops from or to the actual mechanical stops whose positions remain fixed relative to the displacement. An unfavourable displacement of the protective stops with increasing distance from the mechanical stops would lead to a significant reduction in the adjusting path if the protective stops are to prevent overrun, for example through inertia, in the direction of the mechanical stops for reasons of loads.
From U.S. Pat. No. 5,081,586 it is known to set a protective stop in the adjusting path of a vehicle adjuster which can be overrun through a user action by the user operating a corresponding switch on reaching the protective stop. The problem here is that through user actions of this kind a repeated hard run into the mechanical stops which limit the adjusting path can take place, with a corresponding strain on the adjuster.
From U.S. Pat. No. 4,881,020 it is known to set stops in a seat adjuster when opening and closing the vehicle door (corresponding to the driver getting in or out).
Accordingly, what is desired is a method for controlling an adjuster on a motor vehicle which reduces the mechanical strain on the adjusting system of the adjuster through a reduction in the number of adjustments in the mechanical stop without the adjusting path available being significantly restricted by the method.